YA00003081 Excavator Hydraulic Pump 4424246 For Hitachi EX2500-6 EX5500

This mine-grade ultra-heavy-duty high-precision hydraulic main pump assembly features the core OEM part number YA00003081 and is fully compatible with and replaces the iterative part numbers 4455484 and 4424246. Serving as the absolute hydraulic heart of the machine system, it is specifically engineered for Hitachi's giant mining excavators, perfectly matching hundreds of tons-class heavy-duty models such as the EX2500-6 and EX5500. Based on first-principles design, the product undergoes super-high-pressure plunger fluid dynamics optimization to endure extreme all-weather mining loads, ensuring absolute certainty in high-flow power output. The physical packaging dimensions are approximately 1120mm × 650mm × 680mm, with an overall net weight of about 560kg. It features precise OEM-standard position alignment.

"Extreme cleaning and hydraulic fastening: Before using heavy-duty lifting equipment for docking, the environment needs to be treated with dust removal. Before connecting a new pump, all high-pressure pipes and pilot control pipes must be thoroughly cleaned with a specialized cleaning agent. Special hydraulic wrenches must be used to tighten bolts strictly according to the original factory torque for multi-stage symmetrical cross tightening, to prevent uneven stress.

Forced oil filling (core pit avoidance): After the main pump is lifted into place and before starting the engine, clean hydraulic oil must be filled from the oil injection/exhaust port on the top of the pump body. It is strictly prohibited to start dry grinding, otherwise the internal rotating components will undergo irreversible physical erosion within 3 seconds of ignition.

Low pressure exhaust transition: After the first ignition, force the engine to idle at low pressure for 15-20 minutes for automatic exhaust and thermodynamic adaptation of the system. After the oil temperature is normal and all bubbles are cleared, gradually apply the working load."